Variable control means



Feb. 10, 1970 VARIABLE CONTROL MEANS Filed Sept. 22, 196'? 2 Sheets-Sheet 1 H. c. LINDEMANN ETAL 3,494,564 I Feb. 10, 1970 H.' c. LINDEMANN ETAL 3,494,564

VARIABLE CONTROL MEANS Filed Sept. 22, 196'? 2 Sheets-Sheet 2 TENSION DEVICE United States Patent US. Cl. 24245 9 Claims ABSTRACT OF THE DISCLOSURE Means for variably controlling the tension on yarn as it is wound to form a package comprises electrically controlled tension means engaging and applying tension to said yarn, means for supplying power to the tension means and an electrical circuit including the tension means, the power supply and a control unit. The control unit comprises a casing mounted for tilting movement about an approximately horizontal axis, a photoresistive cell mounted in the casing, a light mounted in the casing in position to illuminate the photoresistive cell and a light shield which is freely suspended in the casing in position to hang partially between the light and the photoresistive cell and thereby partially intercept light rays from the light to the photoresistive cell to control the illumination and hence the resistance of the cell. The casing is mechanically connected to means for sensing the size of the package so that as yarn is progressively wound on the package, the resulting increase in size causes tilting of the casing so as to vary the position of the light source and photoresistive cell relative to the freely hanging light shield thereby varying the illumination and hence the resistance of the cell. The photoresistive cell is connected in circuit with the tension means so as to control the actuation of the tension means and thereby regulate the tension of the yarn as the size of the yarn package increases. The light shield is preferably shaped so as to vary the resistance of the photoresistive cell and thereby vary the tension applied to the yarn in accordance with a selected function of package size for example, a straight line fuinction.

The present invention relates to means for controlling yarn tension and to a control unit for regulating a variable yarn tension unit or other device.

In textile machines having yarn feeding means, it is necessary to control the tension at which the yarn is fed. In some instances, it is satisfactory to use fixed or manually adjustable tension means for this purpose. However, in many cases, it is desirable to provide automatically controlled tension means to maintain uniform tension despite variation of factors affecting the tension of the yarn or to provide for variation of yarn tension in accordance with the variation of a selected factor in the operation of the machine.

For example, in the textile industry when yarn is Wound onto a package of selected configuration on a spindle rotating at constant rotational speed, the tension of yarn as it is wound on the package will increase in proportion to the size of the package. If this increase in yarn tension is not compensated, the result will be a poorly formed package which is harder on the outside than in the interior portions. The package may bulge or even collapse due to the non-uniform yarn tension.

In accordance with the present invention, there is provided an automatically compensating tension device for maintaining uniform yarn tension throughout the winding of a selected package. While the tension device in accordance with the invention is particularly useful on winding, coning, up-twisting, down-twisting and similar types of textile machinery, it is also useful in other applications where automatic control of yarn tension is desired.

In accordance with the invention, an electrically con trolled tension means engaging and applying tension to the yarn is controlled by an automatic control unit comprising a casing, a photoresistive unit mounted in the casing, a light source in the casing in position to illuminate the photoresistive unit and a light shield movably mounted in the casing between the light means and the photoresistive unit and movable to intercept a variable amount of light passing from the light source to the photoresistive unit so as to control the illumination and hence the resistance of the photoresistive unit. The photoresistive unit is connected in circuit with the tension means and a power source so as to control the power supplied to the tension means. The position of the light shield is controlled by means for sensing a selected variable factor for example, the size of the package or the tension of the yarn so as to vary the position of the shield and thus the illumination of the photoresistive unit in accordance with the factor selected.

While the control unit in accordance with the invention is particularly useful in the textile industry for automatically controlling yarn tension, it may also be used in other applications.

The invention is illustrated by way of example in the accompanying drawings as applied to winding equipment for winding a yarn to form a package. In the drawings:

FIG. 1 is a somewhat schematic front view of winding equipment incorporating automatic tension control means in accordance with the invention,

FIG. 2 is a vertical section of the control unit shown in FIG. 1,

FIG. 3 is a section taken approximately on the line 33 in FIG. 2,

FIG. 4 is a circuit diagram illustrating a portion of the tension control circuit, and

FIG. 5 is an illustration of a photoresistive unit.

In the drawings, automatic tension control means in accordance with the invention is shown by way of example incorporated in a winding machine for winding yarn Y from a cone C onto a rotating spindle 1 to form a package P of selected size and shape. Yarn from the cone C is directed by yarn guides 2 and 3 through an electrically controlled tension device 5 through a suitable stop motion device 6 for detecting yarn breakage and thence through a yarn feeding guide 7 carried by an arm 8 pivotally mounted at 9 on the machine frame or casing 10. The arm 8 is suitable biased, for example by a weight 11, to swing in a counter-clockwise direction as seen in FIG. 1 so as to maintain a smooth bearing surface or roller 12 associated with the feed guide 7 in light contact with the surface of the package P. It will be seen that roller 12 follows the surface of the package P and hence as the sizeof the package increases, the arm 8 is progressively swung in a clockwise direction about its pivot 9.

The yarn tension device 5 is shown as comprising an electromagnet 15, a central post 16 of ceramic or other abrasive resistant material projecting from the electromagnet and yarn engaging tensions disks 17 and 18 surrounding the post 16 and overlying the electromagnet. The disk 17 nearest the electromagnet is preferably formed at least in part of non-magnetic material while the tension disk 18 farthest from the electromagnet is formed at least in part of magnetic material so as to be attracted toward the electromagnet when the magnet is energized. The tension disk 18 and preferably also disk 17 are rotatable about the central post 16. The yarn Y is guided by the yarn guides 2 and 3 so as to pass between disks 17 and 18 of tension unit and preferably make a partial turn around the central post 16. When the electromagnet 15 is energized, the outer tension disk 18 is attracted toward the magnet so as to press against the yarn passing between the disks aud thereby apply tension to the yarn.

[he amount of tension applied may be varied by varyng the power supplied to the electromagnet 15. The ten- .ion unit may be constructed essentially in accordance vith Mindheim et a1. Patent No. 2,907,535.

The power supplied to the tension unit 5 and hence the ension applied to the yarn Y is variably controlled in tccordance with the invention by a control unit 20. As llustrated in FIGS. 2 and 3, the control unit comprises L casing 21 having a base portion 21a and a removable :over 21b. The casing 21 is pivotally mounted on a supiorting bracket 22 by a pivot bearing 23. As photoresistive :ell 24 is mounted in the casing by one end of a supportng bracket 25 adjustably fixed to the case 21a. Posts 16 carried by the other end of the supporting bracket 25 upport a circuit board 27 carrying selected circuit elements and a socket 28 for an incandescent lamp 30. The amp 30 is positioned so as to illuminate the sensitive urface of the photoresistive cell 24. A window 3-1 of naterial having suitable light filtering properties permits nspection to determine whether the lamp 30 is on while :x-cluding ambient light that would affect the photoresisive cell 24.

A light shield 33 which is at least partially opaque to ight rays is freely suspended between the lamp 30 and hotoresistive cell 24 by a bearing 29 on one of the )osts 26. Depending on the position to which the casing 21 is tilted about its pivot 23, the light shield 33 partialy intercepts light rays passing from the lamp 30 to the )hotoresistive unit 24 so as to control the amount of ight reaching the photoresistive cell and thereby control ts resistance. An edge portion 33a of the light shield 33 s contoured so as to vary the resistance of the photoreistive unit as a selected function of the angular position f the casing 21.

The photoresistive cell 24 has the characteristic that its esistance varies in accordance with the illumination of he sensitive surface of the cell. A photoresistive cell that [38 been found satisfactory for this purpose is a cadmium ulfide or cadmium selenide having its active element 24a .rranged in a sinuous path in a rectangular area 24b as llustrated by way of example in FIG. 5 in order to pro- 'ide a greater effective length in a compact area. As the hield moves between the lamp and the photoresistive ell, light is progressively cut off from an increasing porion of the sensitive material thereby materially increasng the resistance of the cell. The current capacity of the ell is preferably sufficiently great that the cell can be lsed directly in circuit with the tension device 5 so that to amplification of the current is required.

A suitable electric circuit is shown by way of example n FIG. 4. A power supply 34 is provided with terminals '5, 37 and 3-8 supplying regulated direct current voltage f selected values and a common ground return terminal 6. The lamp 30 is connected across terminals 35 and 36. )ne terminal of the tension device 5 is connected to the ommon return terminal 36 of the power supply while be second terminal is connected through the photoresisive unit 24 to terminal 38 and through a resistance 40 vnd crystal diode 41 to terminal 37 of the power supply. Ience current may be supplied to the tension device 5 hrough the photoresistive cell 24 and also through the esistance 40 of selected value. The diode 41 prevents everse flow of current when the resistance value of the thotoresistive cell 24 is low. The power supply 34 preferbly includes suitable means for adjusting the values of oltage supplied at terminals 37 and 38 and thereby adusting the tension of the tension device 5 under selected onditions. The voltage at terminals 35 for supplying curent to the lamp 30 may also be adjustable if desired alhough this is ordinarily not necessary once the correct 'oltage value has been established.

Leads from the lamp socket 28 and from the photoesis'tive unit 24 preferably extend to the circuit board 7 on which the resistance 40 and diode 41 may con- 'eniently by mounted. Connect o s from the c rcui boa d to the power supply and to the tension device 5 are made by a flexible cable 42 which extends out through a grommet 43 in the base 21a of the casing. The grommet 43 fits tightly on the cable and the cover 21b fits tightly on the base 21a of the casing so that when the cover is closed, the casing is sealed so as to prevent entry of light, dirt, lint or other foreign particles into the casing.

A bracket or arm 45 fixed on the casing 21 is connected by an adjustable link 46 to a pivot post 47 on the arm 8 carrying the feed guide 7 of the winder. It will be seen that with the connections shown, rotary movement of the arm 8 about its pivot 9 causes the casing 21 of the control unit 20 to tilt about its pivot 23. The length of the connecting link 46 is adjusted so that when the Spindle of the winder is empty and the arm 8 is hence in its most counter-clockwise position, the casing 21 is in such position that the edge 33a of the freely suspended light shield 33 is in selected relation with respect to the photoresistive cell 24, for example at the edge of the rectangular sensitive area 24b as illustrated FIG. 2. As yarn is wound onto the spindle, the arm -8 is progressively moved about its pivot 9 in a clockwise direction thereby tilting the casing 21 in a clockwise direction about its pivot 23 and causing the shield 33 to move progressively between the lamp and photosensitive cell thereby progressively shading a larger portion of the sensitive area of the cell. As the winding continues, movement of the shield 33 progresses until substantially the entire sensitive area of the cell is obscured when the Winding of a package is completed.

When substantially the entire sensitive area of the photoresistive cell 24 is illuminated at the start of winding of a package, the resistance of the cell is at its minimum value and current is supplied through the cell to the tension device 5 so as to provide a selected initial value of tension applied to the yarn by the device. The initial tension is selected by adjustment of the voltage supplied at terminal 38 of the power supply 34. As an increasing portion of the sensitive area of the cell 24 is shaded as winding of the package continues, the resistance of the photoresistive cell 24 increases. When it reaches a selected value, current is also supplied to the tension device 5 through the diode 41 and resistance 40. During final stages of the winding of the package, the resistance of the photoresistive cell 24 is increased to a value substantially greater than that of resistance 40 so that a major portion of current for the tension device 5 is supplied through the resistance. By selection of a suitable value of the resistance 40 and adjustment of voltages supplied respectively at terminals 37 and 38 of the power supply, the starting tension, finishing tension and characteristics of the tension curve in relation to yarn package diameter can be selected. The tension curve is also affected by the characteristics of the photocell 24 and the shape of the edge 33a of the shield 33.

While the control device 20 is particularly useful for controlling the tension of yarn winding mechanism as illustrated in the drawings, it may also be used for controlling other devices and has the advantage of being completely sealed so as to exclude light, dirt or other foreign particles from the interior of the casing thereby assuring long and reliable operation.

While a preferred embodiment of the invention has been shown and described, it will be understood that modifications may be made within the scope of the appended claims.

What we claim is:

1. Means for variably controlling the tension on yarn as it is wound to form a package comprising electrically controlled tension means engaging and applying tension to said yarn, means for supplying power to said tension means, and a control unit regulating the supply of power to said tension means, said control unit comprising a casing pivotally mounted to tilt about an approximately horizontal axis, a photoresistive unit mounted in said casing, light means in position to illuminate said photoresistive unit, a light shield freely suspended in said casing between said light means and said photoresistive unit and movable relative to said photoresistive unit to intercept a variable amount of light passing from said light means to said photoresistive unit, means for sensing an increase in the size of said package as yarn is progressively wound thereon, means operatively connecting said sensing means with said casing to tilt said casing and thereby vary the position of said light shield relative to said photoresistive unit and hence the resistance of said photoresistive unit in accordance with increase in the size of said package, and an electric control circuit including said tension means, power supply and photoresistive unit to control the tension applied to the yarn by said tension means as the size of said package increases.

2. Control means according to claim 1, in which said photoresistive unit is connected in series with said tension means to reduce the current flowing through said tension means as the resistance of said photosensistive unit is increased.

3. Control means according to claim 1, in which said tension means comprises two tension members between which said yarn runs and an electromagnet which when energized exerts a force urging said tension members toward one another frictionally to engage said yarn.

4. Control means according to claim 3, in which said tension members comprise friction discs at least one of which is rotatable.

5. Control means according to claim 1, in which said sensing means comprises means for feeding yarn to said package.

6. Control means according to claim 5, in which said yarn feeding means comprises a pivoted arm, yarn guiding means carried by said arm and means for positioning said yarn guiding means close to said package as said yarn is being wound on it.

7. Control means comprising a casing, means for movably mounting said casing on a support for tilting movement about an approximately horizontal axis, a photoresistive unit mounted in said casing, light means mounted in said casing in position to illuminate said photoresistive unit, a light shield freely suspended in said casing in position to hang partially between said light meanS and photoresistive unit and partially intercept light from said light means to said photoresistive unit, and means for variably tilting said casing about said axis to vary the position of said light means and said photoresistive unit relative to said freely hanging light shield and thereby vary the light intercepted by said shield to vary the illumination and hence the resistance of said photoresistive unit.

8. In combination with textile machinery having a yarn feed, means for regulating the tension of the yarn in accordance with a selected variable factor, said means comprising electrically controlled tension means engaging and variably applying tension to said yarn, means for supplying power to said tension means and a control unit regulating the supply of power to said tension means, said control unit comprising a casing tiltable about an approximately horizontal axis, a photoresistive unit mounted in said casing, light means in position to illuuminate said photoresistive unit, a light shield freely suspended in said casing between said light means and said photoresistive unit and movable to intercept a variable amount of light passing from said light means to said photoresistive unit and thereby control the illumination and hence the resistance of said photoresistive unit, means for sensing variation of said selected factor, means connecting said sensing means with said casing to tilt said casing and thereby vary the position of said light shield relative to said photoresistive unit and hence the resistance of said photoresistive unit in accordance with variation of said factor, and an electric control circuit including said tension means, power supply and photoresistive unit to control the tension applied to the yarn by said tension means in accordance with the resistance of said photoresistive unit.

9. Control means according to claim 8, in which said light shield has an edge contoured to vary the illumination and hence the resistance of said photoresistive unit in accordance with a selected function as said casing is tilted about said axis.

References Cited UNITED STATES PATENTS 1,967,211 7/1934 Myers 242- 2,253,522 8/1941 Hitchcock 242150 2,432,696 12/ 1947 Swanson 242150 2,907,535 10/ 1959 Mindheim et al.

3,300,161 l/1967 Hermanns 242l54 STANLEY N. GILREATH, Primary Examiner U.S. Cl. X.R. 

